Horizontal fire damper

ABSTRACT

A fire damper construction including a peipheral frame assembly defining interior blade guides, a blade assembly of the pivotally interconnected blade type which is movable within the guides from an open position to closed position to close the fire damper unit upon presence of elevated temperatures and a locking device to maintain the blade assembly in the closed position. A spring and clip assembly affixes to a portion of the interior of the frame assembly and incorporates the locking device. A tension spring biases between the spring and clip assembly and the lowermost blade of the blade assembly to pull the blade assembly to the closed position upon the presence of elevated temperatures and to engage a portion of the blade assembly upon the locking device to prevent movement toward the open position.

United States Patent @191 Kurz [ July 24, 1973 HORIZONTAL FIRE DAMPER John C. Kurz, Philadelphia, Pa. [73] Assignee: Advanced Air, Inc., Philadelphia, Pa. [22] Filed: Sept. 27, 1971 [21] Appl. No.: 183,818

[ 75] Inventor:

52 us. Cl. 160/1 [51] Int. Cl E051 15/20 [58] Field of Search 160/1, 5, 84; 49/7, 6 49/180 [56] References Cited UNITED STATESPATENTS 3,327,764 6/1967 McCabe 160/5 122,615 l/l872 1 Knight 49/7 Primary Examiner-Peter M. Caun Attorney-Karl L. Spivak [57] ABSTRACT A fire damper construction including a peipheral frame assembly defining interior blade guides, a blade assembly of the pivotally interconnected blade type which is movable within the guides from an open position to closed position to close the fire damper unit upon presence of elevated temperatures and a locking device to maintain the blade assembly in the closed position. A spring and clip assembly affixes to a portion of the interior of the frame assembly and incorporates the locking device. A tension spring biases between the spring and clip assembly and the lowermost blade of the blade assembly to pull the blade assembly to the closed position upon the presence of elevated temperatures and to en; gage a portion of the blade assembly upon the locking device to prevent movement toward the open position.

3 Claims, 7 Drawing Figures memaumwr SHEET 1 BF 2 FIG. 3

PATENIED M20973 SHEEIZBFZ FIG. 7

HORIZONTAL FIRE DAMPER BACKGROUND UP THE INVENTION 1. Field of the Invention This invention relates generally to the field of fire safety devices and more specifically, to a horizontal fire damper of the pivotally interconnectingblade type including locking means for engaging one blade of a blade assembly when the blade assembly is moved to a closed position.

2. Description of the Prior Art FIre damper units are well known in the prior art, as exemplified by US. Pat. No. 3,273,632, issued to McCabe on Sept. 20, 1966. Such prior art fire dampers include a frame assembly which defines a damper opening and is suitable for installation in conventional heating, ventilating or air conditioning duct work. A blade assembly secures to the frame assembly by the uppermost blade thereof and includes a plurality of pivotally interconnected blades which are movable from an open, compacted position, wherein the damper opening is substantially unobstructed, to a closed position wherein the damper opening is positively closed against the passage of heated air through the duct system. The prior art fire damper units include thermally activatable retaining means which incorporate a fusible link. of low temperature fuse material to maintain the blade assembly in its open position under normal thermal' conditions. Upon presence of predetermined abnormally hightemperatures, the fusible link will melt to thus release the blade assembly to thereby permit movement of the blade assembly to the closed position to close the damper opening. Some priorart fire dampers of which I am familiarhave been provided with positive acting drive means in the form of a constant tension coil springfor positively moving the plurality of blades of the blade assembly from their open position to their closed position upon melting of the fusible link. A positively actingdrive means of the above described type is illustrated in FIGS. -12 of the above referred to McCabe patent.

It is extremely important that the blade assembly remain in its closed position when a fire breaks out to thereby provide a substantially air tight system to prevent spread of the fire from fire division to fire division through an air duct in which a fire damper unit is disposed. In the prior art fire dampers, prior workers in the field have employed only the=constant tension coil springs, latching assemblies and other clip devices in an attempt to maintain the blades of the blade assembly in the closed position. Under fire conditions, it has been found that the tension spring or the prior art latch and clip devicessometimes fail under the extreme environmental conditions generated by a fire. On occasion, it has. been found thatabnormally high forces can be generated by fires in the duct to overcome the closing forces of the spring or latching devices to thereby permit undesirable opening of the fire damper blades.

SUMMARY OF THE INVENTION The present invention includes a fire damper of the multiple interlocking blade type and incorporates unique locking means to engage one blade of the blade assembly to thereby positively prevent opening of the fire damper unit oncethe blade assembly has been closed by the action of elevated temperatures.

The locking means of the present inventionpositively prevents undesired partial opening of the blade assembly to a position wherein the high temperatures and heated gases of a fire may be permitted to pass by the fire damper. The blade assembly includes a lower blade having a marginal free end which engages a spring and clip assembly which is affixed to the peripheral edge of the damper frame to secure the blades of the blade assembly in the closed position. The locking means include a clip having a locking finger which extends into an opening in one of the blades to maintain the marginal free edge of the lowermost blade in its closed position closely adjacent the inner periphery of the damper frame. The spring and clip assembly further includes a constant tension spring having one end attached to the bottom edge of the lowermost damper blade to positively pull the lowermost damper blade into a locking relation with the locking finger of the clip and locking means.

The present arrangement is extremely compact and is especially suitable for. use for small fire dampers of 6 inch height and under. In such small fire dampers, elongate guide surfaces, such as disclosed in my copending patent application entitled Fire Damper Including Blade Locking Device, filed Aug. 20, 1971, cannot be employed in view of the limited available height.

It is therefore an object of this invention to provide an improved horizontal fire damper of the type set forth.

It is another object of this invention to provide an improved horizontal fire damper including blade locking means to prevent partial opening of a blade assembly when the blade assembly has been urged to its closed position. i p I It is a further object of this invention to provide a novel horizontal fire damper incorporating locking means including constant tension coil springs to pull the free edge of the lowermost blade of a blade assembly into engagement with the inner periphery of the fire damper frame assembly.

It is another object of the present invention to provide a novel horizontal fire damper incorporating locking means whereinthe said locking means include a combination clip and constant tension coil spring which cooperate to pull the blade assembly to a closed position and to positively lockthe blade assembly in the closed position under all environmental conditions which may act upon the tire damper unit.

It is another object of the present invention to provide a novel horizontal fire damper including locking menas wherein the locking means incorporate a combination spring and clip assembly, the clip terminating in a locking finger which cooperates with an opening provided in the lowermost blade of the blade assembly to engage the lowermost blade when. the blade assembly is pulled to its closedposition by action of the constant tension spring. i

It is a further object of the present invention to provide a novel horizontal fire damper that is inexpensive in manufacture, positive in operation and trouble free when in use.

Other objects and a fuller understanding of the invention will be had by referring to the following description and claims of a preferred embodiment thereof, taken in conjunction with the accompanying drawings wherein like reference characters refer to similar parts throughout the several views and in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a horizontal fire damper in open position showing the general arrangement of parts.

FIG. 2 is an enlarged, schematic, cross-sectional view of the device of FIG. 1, showing the blade assembly being pulled into the closed position.

FIG. 3 is an enlarged, schematic cross-sectional view similar to FIG. 2, showing the lowermost portion of the blade assembly being pulled into the area of the spring and clip assembly.

FIG. 4 is an enlarged, schematic, partial, crosssectional view similar to FIG. 2 showing the blade assembly in fully closed and locked position.

FIG. 5 is an enlarged, partial, detail view showing the engagement of the lowermost blade and the locking finger of the spring and clip assembly.

FIG. 6 is an enlarged, partial, detail elevational view taken along Line 6-6 of FIG. 5, looking in the direction of the arrows.

FIG. 7 is a partial, perspective view of the damper assembly in fully closed and locked position.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of my invention selected for illustration in the drawings, and are not intended to define or limit the scope of the invention.

Referring now to the drawings, I show in FIG. 1 a fire damper 10 which includes a frame assembly 12 and a blade assembly 14 movable within the frame assembly from an open position to a closed position to define a barrier to the passage of heated gases. The frame assembly 12 is preferably constructed of a unitary sheet metal member which is roll formed or otherwise machined to include a head 16, a sill 18 and opposed side members 20 extending therebetween to define a damper opening 22. The frame assembly may be of the type fully disclosed in my co-pending application for United States Letters Patent entitled Fire Damper Frames, Ser. No. 173,596, filed Aug. 20, 1971.

The frame assembly 12 is formed to provide vertical, spaced rearward and forward flanges 24, 26 which define a vertical blade guide channel 28 therebetween. Top and bottom horizontal strengthening flanges 30, 32 interconnect with the respective vertical flanges 24, 26 to define the clear damper opening 22. The flanges 24, 26, 30, 32 all lie in the same vertical plane to define the forward and rearward damper mounting frames 34, 36 which serve to secure the fire damper unit 10 to duct work or other construction (not shown) in conventional manner. The blade assembly 14 comprises a plurality of individual, horizontally interlocking blades 14a, 14b, 14c, 14d which ride within the blade guide channel 28 from an open position as illustrated in FIG. 1 to a closed and locked position as illustrated in FIG. 7. The top blade l4a'pivotally affixes to the frame assembly head 16 in a pivotal connection 38 in a manner to prevent thepassage of heated gases between the blade assembly 14 and the head 16 of the frame assem-' bly 12. Sufficient blades 14a, 14b, 14c, 14 d are provided to fully close the damper opening 22 when the blade assembly is urged to its closed position (FIG. 7).

As best seen in FIGS. 15, a spring and clip assembly 40 secures to the frame sill 18 in secure manner such as by spot welding or by employing rivets 42, 44 in well known manner. The clip assembly is generally Z- shaped in cross sectional configuration and includes a mounting leg 46 which rests upon the frame sill 18 and is secured thereto by the rivets 42, 44. A locking leg 48 spaces above the mounting leg 46 a distance defined by the vertical spacer 50. The locking leg 48 terminates forwardly in a locking finger 52 which cooperates with the lowest damper blade 144 to maintain the blade assembly 14 in its closed position in the manner hereinafter more fully set forth. The edge of the locking leg 48 bends downwardly substantially at the traverse midsection of the spring and clip assembly 40 to provide a vertical support 54 upon which the spring shaft 56 horizontally mounts. The spring 58 winds about the spring shaft 56 and is of the constant tension type wherein the spring continuously tends to coil about its spring shaft 56.

The blade end 60 of the spring 58 affixes to the lowermost damper blade 14d slightly above its lowest edge 62 and is secured thereto in a riveted connection. The connection between the spring end 60 and the blade 14d employs a large head rivet 64 and opposed flat washer 66 which cooperate to insure a large contact area 68 between the spring end 60 and the damper blade 14d for blade guiding purposes as hereinafter more fully set forth. Preferably, two spring and clip assemblies 40 are employed and have their springs 58 respectively connected near the lateral edges of the lowermost damper blade 14d for optimum blade guiding operation.

As illustrated in FIGS. 2-5, the locking finger 52 extends horizontally in spaced relation above the frame assembly sill 18 and positions within the blade guide channel 28 with its free terminal 70 pointing outwardly toward the rearward flange 24. A space 72 is defined between the vertical rearward flange 24 and the free terminal 70 of the clip of sufficient width to permit passage of the lowest edge 62 of the blade 14d when the blade assembly 14 is urged to its closed position by the action of the springs 58. See FIG. 3. It should be noted that each spring 58 unwinds from its spring shaft 56 in a direction toward the rearward flange 24 and connects to the blade 14d in a manner to urge the lowest edge 62 of the blade 14d toward the space 72 for blade locking purposes when the blade assembly is urged to its closed position. It will be noted that the width of the lowest edge 62 of the damper blade 14d is only slightly less than the width of the space 72. In this manner, the blade edge 62 is urged past the locking finger 52 when the blade assembly is closed, but opening forces will be effectively surpressed. The bias of the springs 58 must be sufficiently strong to pull the lowest edge 62 of the damper blade 14d past the free terminal 70 of the spring and clip assembly 40 to thereby positively close the fire damper when the blade assembly 14 is urged to its closed position as in FIG. 7.

The lowest blade 14d is provided with a pairiof horizontally aligned, transversely spaced openings 74 which register with the free terminals 70 of the locking fingers 52 when the blade assembly is urged to its closed position as in FIG. 7. It will be noted that the overall height of the blade assembly 14 is greater than the height of the frame assembly 12 so that when the blade assembly 14 is urged to its closed position, the blades 14a, 14b, 14c, 14d will diagonally position within the blade guide channel 28 and in particular, the lowest blade 14d will angularly incline with respect to the horizontal disposition of the locking leg 48 and its extending locking finger 52. In this manner, when the blade openings 74 register over the locking fingers 52, the diagonal orientation of the lowermost blade 14d serves to engage the locking finger 52 within the opening 74 to positively prevent opening of the blade assembly 14 upon the application of axial forces against the blade assembly 14 such as may be generated in the duct work (not shown) during emergency conditions, such as a fire. The springs 58 constantly bias the lowest edge 62 toward the spring shafts 56 to thereby prevent accidental release of the openings from engagement with the locking fingers 52 once the blade assembly has closed.

In operation, the blade assembly is normally retained in open position as in FIG. 1 by a fusible link (not shown) whereby the blades interfold and position at the top of the frame assembly 12 to define a damper opening 22 for normal passage of air therethrough. Upon application of predetermined elevated temperatures at the fire damper unit 10, the fusible link (not shown) will melt in well known manner to release the blade assembly. The springs 58 serve to urge the blade assembly tothe closed position of FIG. 7 by pulling the lowermostblade 14d toward the frame assembly sill 18. See FIG. 2. The springs 58 serve to pull the lowest, edge 62 of the blade 14d past the spring andclip assembly 40 by urging the lowest edge 62 into the space 72 defined between the free terminal 70 of the locking finger 52 and the rearward flange 24. See FIG. 3. Once the lowest edge 62 has cleared the free terminal 70 of the spring and clip assembly 40, the springs 58 further bias the blade assembly 14 to its fully closed position wherein the spaced openings 74 register over the free terminals 70. The blade 14d is angularly oriented with respect to the spring and clip assembly 40 when the blade assembly is in the fully closed position causing the locking fingers 52 to engage within the blade openings 74. See FIGS. 4 and 5. It will be noted that the springs 58 continue to bias the lowest blade 14d when the blade assembly 14 is urged to its closed position and serve to maintain the locking fingers 52 in seated relation within the openings 74. Thus, axial forces in the direction of the arrow 76 (FIG. 2) cannot open the blade assembly. Rather, such forces would tend to more tightly lock the blade assembly 14 in the said closed position. Axial forces acting in a direction opposite to the arrow 76 would be effectively counteracted by the combination of the forces of the springs 58 and the angular orientation of the blade 14d.

When it is desired to open the blade assembly 14 after ithas moved to the closed position of FIG. 7, it is necessary to manually urge the lowest edge 62 of the blade 14 toward the rearward flange 24 against'the bias of the springs 58 in a manner to position the lowest edge 62 within the space 72 provided between the free terminal 70 and the rearward flange 24. Once the openings 74 have cleared the respective locking fingers 52, the blades may be urged upwardly against the bias of the springs 58 until they reach their fully interfolded position at the head 16 of the frame assembly 12 to once again clear the damper opening 22. A new fusible link and necessary connecting linkage (not shown) can be reinstalled in the usual manner to maintain the blade assembly 14 in the open position of FIG. 1.

I claim:

1. In a fire damper construction of the type including a peripheral frame including a horizontal head and sill and vertical interconnecting sides and having a blade guide channel defined by spaced pairs of forward and rearward vertical flanges wherein the blade guide channel frames a damper opening having a width and a height, the combination of A. a blade assembly movable within the blade guide channel from an open position to a closed position,

1. said blade assembly comprising a plurality of individual horizontally interlocking blades including a top blade, a bottom blade and a plurality of immediate interconnected blades,

a. the said top blade being pivotally affixed to the frame head,

b. the said bottom blade having a lowest edge and being provided with a locking opening,

c. the lowest edge being relatively narrowwith respect to the width of the blade guide channel; and

B. a spring and clip assembly affixed to the frame in position to coact with the blade assembly,

1. said spring and clip assembly including a coil spring having an end portion thereof connected to the blade assembly in a riveted connection, a. said spring continuously biasing the blade assembly to the closed position,

b. said riveted connection being positioned on the bottom blade near the said locking openg,

c. the said locking opening and rivetedconnection being positioned near the said lowest edge,

2. the spring and clip assembly being generally Z- shaped in cross sectional configuration and having a horizontal mounting leg secured to the frame sill, r a. said spring and clip assembly including a horizontal locking leg which is parallel to and spaced above the frame sill,

b. the locking leg being connected to the mounting leg by a vertical spacer which interconnects the forward edge of the mounting leg to the rearward edge of the locking leg,

c. the locking leg terminating forwardly in a locking finger,

(.l) the said locking finger being positioned in stationary, parallel relationship above the frame sill,

(.2) the locking finger interacting with the blade assembly at the locking opening thereof when the blade assembly is moved to its closed position to lock the blade assembly in the closed position,

(.3) the locking finger defining a narrow blade assembly edge passing space between the locking finger and the forward vertical flange, 7

- (.4) said passing space being slightly wider than the width of the lowest edge,

(.5) the said riveted connection being positional near the lowest edge and the said spring guiding the lowest edge into the passing space whereby the spring continuously 7 8 pulls the blade assembly into locking engage- 3. The invention of claim 2 wherein the bottom blade "lent the said locking fingerangularly inclines with respect to the horizontal dispo- 2. The invention of claim 1 wherein the overall height of the blade assembly is greater than the height of the damper opening when the blade assembly is fully opened to a position wherein all of the blades lie in the posltlonsame vertical plane.

sition of the locking leg and its extending locking finger when theblade assembly is disposed in its said closed 

1. In a fire damper construction of the type including a peripheral frame including a horizontal head and sill and vertical interconnecting sides and having a blade guide channel defined by spaced pairs of forward and rearward vertical flanges wherein the blade guide channel frames a damper opening having a width and a height, the combination of A. a blade assembly movable within the blade guide channel from an open position to a closed position,
 1. said blade assembly comprising a plurality of individual horizontally interlocking blades including a top blade, a bottom blade and a plurality of immediate interconnected blades, a. the said top blade being pivotally affixed to the frame head, b. the said bottom blade having a lowest edge and being provided with a locking opening, c. the lowest edge being relatively narrow with respect to the width of the blade guide channel; and B. a spring and clip assembly affixed to the frame in position to coact with the blade assembly,
 1. said spring and clip assembly including a coil spring having an end portion thereof connected to the blade assembly in a riveted connection, a. said spring continuously biasing the blade assembly to the closed position, b. said riveted connection being positioned on the bottom blade near the said locking opening, c. the said locking opening and riveted connection being positioned near the said lowest edge,
 2. the spring and clip assembly being generally Z-shaPed in cross sectional configuration and having a horizontal mounting leg secured to the frame sill, a. said spring and clip assembly including a horizontal locking leg which is parallel to and spaced above the frame sill, b. the locking leg being connected to the mounting leg by a vertical spacer which interconnects the forward edge of the mounting leg to the rearward edge of the locking leg, c. the locking leg terminating forwardly in a locking finger, (.1) the said locking finger being positioned in stationary, parallel relationship above the frame sill, (.2) the locking finger interacting with the blade assembly at the locking opening thereof when the blade assembly is moved to its closed position to lock the blade assembly in the closed position, (.3) the locking finger defining a narrow blade assembly edge passing space between the locking finger and the forward vertical flange, (.4) said passing space being slightly wider than the width of the lowest edge, (.5) the said riveted connection being positional near the lowest edge and the said spring guiding the lowest edge into the passing space whereby the spring continuously pulls the blade assembly into locking engagement with the said locking finger.
 2. the spring and clip assembly being generally Z-shaPed in cross sectional configuration and having a horizontal mounting leg secured to the frame sill, a. said spring and clip assembly including a horizontal locking leg which is parallel to and spaced above the frame sill, b. the locking leg being connected to the mounting leg by a vertical spacer which interconnects the forward edge of the mounting leg to the rearward edge of the locking leg, c. the locking leg terminating forwardly in a locking finger, (.1) the said locking finger being positioned in stationary, parallel relationship above the frame sill, (.2) the locking finger interacting with the blade assembly at the locking opening thereof when the blade assembly is moved to its closed position to lock the blade assembly in the closed position, (.3) the locking finger defining a narrow blade assembly edge passing space between the locking finger and the forward vertical flange, (.4) said passing space being slightly wider than the width of the lowest edge, (.5) the said riveted connection being positional near the lowest edge and the said spring guiding the lowest edge into the passing space whereby the spring continuously pulls the blade assembly into locking engagement with the said locking finger.
 2. The invention of claim 1 wherein the overall height of the blade assembly is greater than the height of the damper opening when the blade assembly is fully opened to a position wherein all of the blades lie in the same vertical plane.
 3. The invention of claim 2 wherein the bottom blade angularly inclines with respect to the horizontal disposition of the locking leg and its extending locking finger when the blade assembly is disposed in its said closed position. 